Researchers trace activity of rare whooping cranes

Saturday

Nov 24, 2012 at 2:54 PM

JANET McCONNAUGHEYThe Associated Press

NEW ORLEANS — Whooping cranes introduced to the wild in southwestern Louisiana are the focus of intense research aimed at finding out where they go, what they eat and what else they do with their time.

Nobody has ever looked for such detailed information about how captive-bred whoopers live in the wild, said John B. French Jr., research manager at the U.S. Geographical Survey's Patuxent Wildlife Research Center in Maryland, where the cranes were bred.

"I'm really eager to see what they can come up with there," he said.

The graceful cranes, which stand nearly 5 feet tall with a 7 ½-foot wingspan, are among the world's rarest birds. Just over 500 survive, all descended from 15 that lived in coastal Texas in the 1940s, French said. There are now four flocks; the 250 or so birds that migrate between Texas and northern Canada make up the only natural and self-sustaining flock.

The smallest and newest is based at White Lake, the area near Gueydan where Louisiana's last flock lived in the 1930s. Twenty-six whoopers have been released in two groups since early 2011. Fourteen are still alive, including two from the first group of 10. Another 14 are expected Nov. 28.

They, too, will be fitted with radio transmitters so researchers can keep tabs on their whereabouts and go out regularly to watch them. That requires a spotting scope so watchers can stay at least 200 feet away, said lead researcher Sammy King of the USGS Louisiana Cooperative Fish and Wildlife Research Unit.

"The last thing you want to do is disturb the birds" or let them get used to people, he said.

King said Tandi Perkins and Vladimir Dinets, research associates with the LSU AgCenter and USGS, and Louisiana Department of Wildlife and Fisheries biologist Sara Zimorski, do most of the field work.

If a transmitter stops moving, they must look for a carcass, both to learn what killed the crane and to retrieve the transmitter to use on another bird. After the record Mississippi River floods of 2011, one bird's remains were found in a harvested cornfield in the Morganza Spillway, 80 miles from White Lake. A predator apparently dragged it into the standing corn.

That's far from a distance record for cranes in this group. One flew into Arkansas for a day last summer, while another spent a day 150 miles away at Catahoula Lake, King said.

French said the flock that nests in Canada hatches 30 to 40 chicks each year, while captive birds at Patuxent and at the International Crane Foundation in Baraboo, Wis., produced 29 this year.

Three died before they could fly. A fourth — one of six led by ultralight plane on a migration route from Wisconsin to Florida — died on the operating table after breaking a leg on a landing in Illinois. The other five in that group reached their wintering grounds at St. Marks National Wildlife Reserve in Florida on Friday. Six hatched in Baraboo were released Oct. 29 at Horicon National Wildlife Refuge in Wisconsin to join the flock, most of which was still in Wisconsin on Friday.

Perkins said most research about what whooping cranes do and eat has involved the Texas-Canada flock. The Wisconsin-Florida flock numbers about 100, with another 20 in a non-migrating flock that never really took hold in Florida. Like Louisiana's, that one was considered experimental.

"There are really a lot of unknowns for this introduced population," Perkins said.

She spends at least a day each week in the field, keeping notes on where the birds are, how they're distributed, what sort of habitat they're using and what they're doing.

For instance, how much time do they spend in natural habitat compared to crawfish ponds and rice fields? Do they spend their nights in the artificial ponds or go to another pond? Whooping cranes roost on the ground, not in trees, and standing in shallow water protects them from some predators while they sleep.

King said predators have killed fewer than he expected so far, though that may change in two or three years. "Once birds start nesting they may be more vulnerable," he said.

For now, the idea is to collect baseline information that can serve as a basis for comparison in the future.

That should help biologists figure out the best natural habitat, how many birds it can support, how habitat quality changes and whether birds raised differently act differently, King said.

Whooping cranes eat almost anything smaller than they are — snakes, turtles, fish, crabs, clams, crawfish, frogs, rodents, small birds, berries and tubers. Perkins said they spend 60 to 80 percent of the time foraging in fields.

"A good share of that is probing into the ground," apparently for tubers, she said.

The cranes may eat a bit of farmers' crops, though far less than the huge flocks of other wading birds that sometimes gather at farm ponds. But Perkins said every farmer she's talked to has been interested, curious about whoopers' history in Louisiana and elsewhere, and sometimes very helpful finding birds.

She said, "I have farmers texting me — 'Oh, I don't see the cranes. Did they move? I was concerned because we hunt — what will that do to the birds?'"